TLR4 was initially discovered as a receptor which recognizes lipopolysaccharide of Gram negative bacteria and activates the natural immunity system. However, in recent years, it has been elucidated that not only does TLR4 activate such natural immunity reactions for preventing infections, but also recognizes various endogenous ligands produced in said various diseases and activates various cells playing central roles in the said diseases. Moreover, it has been reported that expression of TLR4 is accentuated in lesions of various diseases and that onset and progression of diseases in disease model animals are markedly suppressed in TLR4 knockout mouse and mutant mouse. Accordingly, it is suggested that TLR4 plays an important role in autoimmune disease and/or inflammatory disease, and diseases such as cardiac disease, renal disease, liver disease, central nervous system disease, infectious disease, malignant tumor, sepsis, septic shock and the like.
In addition to such diseases, the relationship to ischemia-reperfusion injury (ischemia reperfusion injury: IRI) caused by reperfusion of blood flow to organs and tissues in ischemic condition upon organ transplantation and the like, is also reported. High Mobility Group Box 1 (HMGB-1), which is one of TLR4 endogenous ligands, increases in transplanted organ. Moreover, the transplanted organ derived from donor with genetically impaired TLR4 function shows resistance to IRI-associated dysfunction. From such publicly known knowledge, it is suggested that TLR4 signal due to HMGB-1 plays an important role in IRI (Non-Patent Document 1, Non-Patent Document 2).
As a result, TLR4 signaling inhibitors (may also be called “TLR4 inhibitors”) are anticipated to be preventive and therapeutic drugs of autoimmune disease and/or inflammatory disease or diseases such as cardiac disease, renal disease, liver disease, central nervous system disease, infectious disease, malignant tumor, sepsis, septic shock, etc.
In Patent Document 1 the following compound

(wherein, each symbol is described in the description in the said literature) is reported as a TLR4 signaling inhibitor.
In Patent Document 2 the following compound

(wherein, each symbol is described in the description in the said literature) is reported as a TLR4 signaling inhibitor.
In Patent Documents 3 and 4 the following compound

(wherein, each symbol is described in the description in the said literature) is reported as TLR4 signaling inhibitor.